Description: (Taken directly from the application) The purpose of Core B is to set up a small tissue culture room dedicated to the growth and handling of embryonic stem (ES) cells that will be used for gene targeting experiments. These experiments are extremely time-consuming, but can be easily ruined by mycoplasma contamination, which exists in many established cell lines being handled in our regular tissue culture rooms. This Core will benefit primarily Project 1, which aims at the knockout of genes encoding some of the uroplakins, Project 4 which will knockout p53 in urothelial cells.